Smoke rises in the North Korean border town of Kaesong, seen from Paju, South Korea, Tuesday, June 16, 2020. South Korea says that North Korea has exploded an inter-Korean liaison office building just north of the tense Korean border. (Yonhap via AP)

South Korean Marines patrol on Yeonpyeong Island, South Korea, Tuesday, June 16, 2020. North Korea blew up an inter-Korean liaison office building just north of the heavily armed border with South Korea on Tuesday in a carefully choreographed display of anger that sharply raises tensions on the Korean Peninsula and puts pressure on Washington and Seoul amid deadlocked nuclear diplomacy. (Kim In-chul/Yonhap via AP)

Smoke raising in the North Korean border town of Kaesong is seen from Paju, South Korea, Tuesday, June 16, 2020. North Korea blew up an inter-Korean liaison office building just inside its border in an act Tuesday that sharply raises tensions on the Korean Peninsula amid deadlocked nuclear diplomacy with the United States. (Yonhap via AP)

South Korean army's K-55 self-propelled howitzers are seen at the border with North Korea, South Korea, Tuesday, June 16, 2020. North Korea blew up an inter-Korean liaison office building just inside its border in an act Tuesday that sharply raises tensions on the Korean Peninsula amid deadlocked nuclear diplomacy with the United States. (AP Photo/Ahn Young-joon)

South Korean Marines patrol on Yeonpyeong Island, South Korea, Tuesday, June 16, 2020. North Korea blew up an inter-Korean liaison office building just north of the heavily armed border with South Korea on Tuesday in a carefully choreographed display of anger that sharply raises tensions on the Korean Peninsula and puts pressure on Washington and Seoul amid deadlocked nuclear diplomacy. (Kim In-chul/Yonhap via AP)

FILE - In this Sept. 14, 2018, file photo, South Korea's Unification Minister Cho Myoung-gyon, center left, and Ri Son Gwon, chairman of the North's Committee for the Peaceful Reunification, center right, attend at an opening ceremony for two Koreas' first liaison office in Kaesong, North Korea. South Korea on Tuesday, June 16, 2020, says North Korea blew up an inter-Korean liaison office amid rising tensions between the rivals. (Korea Pool/Yonhap via AP, File)

South Korean Marines patrol on Yeonpyeong Island, South Korea, Tuesday, June 16, 2020. North Korea blew up an inter-Korean liaison office building just north of the heavily armed border with South Korea on Tuesday in a carefully choreographed display of anger that sharply raises tensions on the Korean Peninsula and puts pressure on Washington and Seoul amid deadlocked nuclear diplomacy. (Kim In-chul/Yonhap via AP)

A man watches a TV screen showing a news program about the demolition of the inter-Korean liaison office building, at the Seoul Railway Station in Seoul, South Korea, Tuesday, June 16, 2020. North Korea blew up an inter-Korean liaison office building just north of the heavily armed border with South Korea on Tuesday in a dramatic display of anger that sharply raises tensions on the Korean Peninsula and puts pressure on Washington and Seoul amid deadlocked nuclear diplomacy. The letters read "North Korea, demolition of the inter-Korean liaison office building in Kaesong." (Kim Do-hun/Yonhap via AP)

A North Korean flag flutters in the wind at a military guard post in Paju, at the border with North Korea, South Korea, Tuesday, June 16, 2020. North Korea blew up an inter-Korean liaison office building just inside its border in an act Tuesday that sharply raises tensions on the Korean Peninsula amid deadlocked nuclear diplomacy with the United States. (AP Photo/Ahn Young-joon)

Military guard posts of North Korea, rear, and South Korea, foreground, are seen in Paju, at the border with North Korea, South Korea, Tuesday, June 16, 2020. North Korea blew up an inter-Korean liaison office building just inside its border in an act Tuesday that sharply raises tensions on the Korean Peninsula amid deadlocked nuclear diplomacy with the United States. (AP Photo/Ahn Young-joon)

South Korean Marines patrol on Yeonpyeong Island, South Korea, Tuesday, June 16, 2020. North Korea blew up an inter-Korean liaison office building just north of the heavily armed border with South Korea on Tuesday in a carefully choreographed display of anger that sharply raises tensions on the Korean Peninsula and puts pressure on Washington and Seoul amid deadlocked nuclear diplomacy. (Kim In-chul/Yonhap via AP)

A South Korean army soldier patrols at the Unification Bridge, which leads to the Panmunjom border village in the Demilitarized Zone in Paju, South Korea. Tuesday, June 16, 2020. North Korea blew up an inter-Korean liaison office building just inside its border in an act Tuesday that sharply raises tensions on the Korean Peninsula amid deadlocked nuclear diplomacy with the United States. (AP Photo/Ahn Young-joon)

Barricades are placed near the Unification Bridge which leads to the border village of Panmunjom in the Demilitarized Zone in Paju, South Korea. Tuesday, June 16, 2020. North Korea blew up an inter-Korean liaison office building just inside its border in an act Tuesday that sharply raises tensions on the Korean Peninsula amid deadlocked nuclear diplomacy with the United States. (AP Photo/Ahn Young-joon)

In this photo provided by South Korea Defense Ministry via Yonhap News Agency, an image from a thermal observation device showing the explosion of an inter-Korean liaison office building in North Korea's Kaesong is seen from Paju, South Korea, Tuesday, June 16, 2020. North Korea blew up an inter-Korean liaison office building just inside its border in an act Tuesday that sharply raises tensions on the Korean Peninsula amid deadlocked nuclear diplomacy with the United States.(South Korea Defense Ministry/Yonhap via AP)